[pnfs] [PATCH 8/9] layoutrecall: add commentary

[Benny Halevy]

Add some FIXME commentary on remaining work to be done
for layout recall to synchronize layout returns with in-flight
I/Os and conflicting LAYOUTGETs and LAYOUTRETURNs

Signed-off-by: Benny Halevy <bhalevy at panasas.com>
---
 fs/nfs/delegation.c |    9 ++++++++-
 1 files changed, 8 insertions(+), 1 deletions(-)

diff --git a/fs/nfs/delegation.c b/fs/nfs/delegation.c
index e6a909a..16cf3f6 100644
--- a/fs/nfs/delegation.c
+++ b/fs/nfs/delegation.c
@@ -380,7 +380,14 @@ static int recall_layout_thread(void *data)
 	args->result = 0;
 	complete(&args->started);
 
-//??? commit the files first ???
+/* FIXME: need barrier here:
+   pause I/O to data servers
+   pause layoutgets
+   drain all outstanding writes to storage devices
+   wait for any outstanding layoutreturns and layoutgets mentioned in
+   cb_sequence.
+   then return layouts, resume after layoutreturns complete
+ */
 
 	if (args->rl.cbl_recall_type == RECALL_FILE) {
 		pnfs_return_layout(args->inode, &args->rl.cbl_seg);
-- 
1.5.2.5